Survey of the existing literature reporting the effects of alcohol on
psychomotor and cognitive skills illustrates a substantial deficit in
research using women as subjects compared to men. Lex (1991) suggested
that this neglect has been primarily a function of widely held erroneous
beliefs that sociocultural factors protect females from developing
alcohol abuse and that alcohol abuse is similar in men and women.
Research, however, indicates that age of onset, development and symptoms
of alcoholism, and detrimental physiological effects are different for
men and women. This underscores an increased need for research
investigating the physiological and behavioral effects of alcohol in
women (e.g., Dougherty, Cherek, & Bennett., 1995; Galanter, 1995;
Lex, 1991).

A particular area in which women have been neglected as research
subjects has been the study of the effects of alcohol on psychomotor and
behavioral tasks and tolerance to the effects of alcohol on these tasks
across repeated trials. Tolerance is observed as a decrease in the
effect, whereas sensitization is evidenced by an increase in the effect
on the measured response. Tolerance has been observed more readily and
has been researched much more extensively than sensitization (Bennett,
1992; Newlin & Thompson, 1991). Tolerance can be described in two
ways: (1) Chronic tolerance is observed as a decrease in the magnitude
of an effect of alcohol with repeated exposures; and (2) acute tolerance
is observed within the course of the elimination of a single exposure
and is characterized by a reduced alcohol effect on the descending limb
of the breath alcohol concentration curve (BAC) when compared to the
ascending limb.

The lack of data comparing alcohol effects on psychomotor tasks in
male and female social drinkers suggests that a concerted effort in this
area is warranted. For example, Cherpitel (1996) recently reported
gender differences in proportions of different types of
alcohol-associated injuries (such as falls) among emergency room
patients. Inasmuch as no significant gender differences in rates of
alcohol consumption were reported in an earlier survey of emergency room
patients admitted for unintentional alcohol-related injuries (Cherpitel,
1994), of interest is evaluating gender differences in acute
alcohol-induced decrement in motor functioning (especially repeated
exposure effects) to help clarify such findings.

In previous study of gender differences in alcohol effects, Niaura,
Nathan, Frankenstein, Shapiro, and Brick (1987) found no gender
differences in the effect of a single moderate bolus of alcohol on a
rotary pursuit task. In contrast, the study presented here directly
compares the effects of higher alcohol doses on a rotary pursuit task
using a cumulative dosing procedure. Cumulative dosing was implemented
in favor of a larger single dose in order to simulate natural drinking
behavior and to result in greater peak intoxication than examined
previously (Niaura et al., 1987). Moreover, subjects were given two
exposures to cumulative alcohol dosing, and dosage was adjusted for
female subjects to attain similar peak breath alcohol concentrations to
their male counterparts. Measurements were made along the ascending and
descending limbs of the BAC curves and compared. Specific questions of
interest in this study were: (1) Is acute tolerance to the behavioral
effects of alcohol evidenced similarly in females and males? and (2)
would a second day of alcohol exposure have a differential outcome on
the alcohol effect between male and female subjects.

Method

Subject Recruitment

Using newspaper advertisement for "social drinkers," we
recruited 10 men and 10 women ages 22 to 39. Callers who reported
drinking six or more alcoholic beverages per week and who reported no
current psychiatric problems or medical problems were invited to visit
the laboratory for an on-site interview. Once at the laboratory,
applicants underwent a structured clinical interview (SCID-NP; Spitzer,
Williams, Gibbon, & First, 1988) to determine whether they met
DSM-III-R (APA, 1987) criteria for any mental illness and/or substance
use disorder. In addition, subjects completed a medical questionnaire,
on which they self-reported current alcohol use in terms of a specified
number of drinks per day or week, where a "drink" was defined
as 12 oz of beer, 4 oz of wine, or 1 oz of liquor or a mixed drink.
Applicants who currently met DSM-III-R criteria for any psychoactive
substance use disorder or other psychiatric illness or who self-reported
significant medical problems were excluded. Past psychiatric illness or
a substance use disorder in remission was not an exclusion criterion.
The study was described as a study of the effects of alcohol on motor
performance and informed consent was obtained. To encourage subjects to
perform as well as possible on the rotary pursuit task, a portion of
subject payment was contingent on rotary pursuit task performance. With
the addition of flat rate bonus payment for punctuality and study
completion, subjects earned a total of approximately $50.00 per day. All
psychometric instruments, consent forms, and methods were approved by
the University's Internal Review Board.

Subject Demographics

Mean ages of male and female subjects were 31.4 [+ or -] (SD) 5.9,
and 30.7 [+ or -] 5.4, respectively. Mean subject weights were 82.7 [+
or -]12.9 kg for men and 69.7 [+ or -] 9.8 kg for women. The racial
composition of subjects was as follows: Men: African-American (n = 5),
Hispanic (n = 4), Caucasian (n = 1). Women: African-American (n = 4),
Hispanic (n = 1), Caucasian (n = 5). The average number of years of
alcohol consumption was 14.8 [+ or -] (SD) 5.1 for males and 13 [+ or -]
5.9 for females. Male subjects reported drinking a median of 15.5 drinks
per week, whereas female subjects drank a median of 10.0 drinks per
week. Finally, male subjects reported having consumed alcohol for an
average of 14.8 [+ or -] 5.1 years, and female subjects reported having
consumed alcohol for 13.0 [+ or -] 5.9 years. Independent t tests
indicated that male subjects were significantly heavier than female
subjects, but that gender differences in age, years of alcohol
consumption, or drinks per week were not significant.

Beverage Administration

Beverages were administered by a research assistant blind to the
drink's content. Subjects were allowed 15 rain to consume each
drink. Following ingestion of each beverage, subjects subjectively rated
its "shot" equivalent and expected degree of intoxication on
two, 0-10 point scales on a questionnaire. On the placebo days (Days 3
and 5, see below), subjects received three beverages, each consisting of
240 ml of lemon-lime soda pop with peppermint flavoring and 1 ml alcohol
dispensed along the inner brim of the paper cup in order to provide an
illusory "bouquet." On alcohol dose days (Days 4 and 6, see
below), subjects received three beverages, each containing 0.35 g/kg of
95% alcohol (including the 1 ml dispensed along the brim) brought to a
240 ml volume with lemon-lime soda pop and peppermint flavoring. In
order to achieve similar peak breath alcohol content levels (BACs)
between men and women, dosage for female subjects was calculated based
on 92% of body weight (Hindmarch, Keff, & Sherwood, 1991).

Rotary Pursuit

The rotary pursuit task was performed on a Photoelectric Rotary
Pursuit Apparatus (Model 32534, Lafayette Instruments, Inc.). The
apparatus consisted of a wand connected by a cord to a turntable-like
base unit, which was placed on a tabletop. The base unit emitted a 2-cm
x 2-cm light source beneath a clear glass top in a circular pattern with
a radius of 13 cm at 30 revolutions per minute. The tip of the wand was
bent at 90 [degrees] from the long (handle) axis and contained a
photoreceptive cell. The subject was instructed to maintain the tip of
the wand over the circling light source as long as possible without the
tip of the wand contacting the glass surface of the base unit. Subjects
were reminded that a portion of their payment was a function of their
performance. Each session lasted 120 s, and a stop-clock apparatus
connected to the base unit tabulated cumulative seconds of photocell contact with the circling light source. Subjects performed the task
while standing in front of the base unit opposite the experimenter and
were unable to see the stop clock readout. However, a tone sounded while
contact was being maintained, providing feedback to the subject.

Testing Schedule

The study lasted for 6 days, with six performance sessions scheduled
across each day. Subjects remained in a TV lounge between sessions, and
a standard diet was provided consisting of a 100 g bagel at 0815 hr and
a lunch at 1215 hr. On each day, subjects arrived at the laboratory at
0800 hr, and breath and urine samples were obtained to ensure no alcohol
or drug use. Breath alcohol concentration (BAC) levels were determined
in this study with an Alco-Sensor III (Intoximeters, Inc; St. Louis,
Mo). The presence of drugs in urine (determined by the EMIT d.a.u.
immunoassay) resulted in removal of the subject from study. Presence of
alcohol in the breath sample resulted in the removal of the subject for
the day. On each day of the study, subjects underwent a single rotary
pursuit testing session at each of the following six times: 0900 hr,
1000 hr, 1100 hr, 1200 hr, 1400 hr, and 1600 hr. At 1615 hr, subjects
were evaluated by staff, paid, and released for the day.

The first 2 days of the study were a training period, when subjects
performed the rotary pursuit task across the day with no beverage
ingestion. On the 2nd day, subjects also underwent a physical
examination at the research clinic, at which time subjects were weighed.
On each subsequent day, subjects received either three placebo drinks or
three 0.35g/kg alcohol drinks. Beverages were administered after the
first (baseline) rotary pursuit session, and after the second and third
sessions - at 0915 hr, 1015 hr, and 1115 hr, respectively. This allowed
45 min for alcohol absorbtion prior to the next testing session. Prior
to each rotary pursuit session, BAC levels were obtained. The daily
regimen was as follows:

Day 1: Training Day 2: Training Day 3: Placebos Day 4: Alcohol doses
Day 5: Placebos Day 6: Alcohol doses

Data Analysis

Data are represented both as total seconds of contact time in each
session as well as expressed on alcohol days as the decreases of
photocell contact (performance decrement) compared to the subject's
contact time recorded in the pre-alcohol baseline session. BAC and
performance values were compared across sessions using multifactorial repeated-measures ANOVAs with time of day and alcohol administration day
(Day 4 vs. Day 6) as the repeated measures, and gender as the
between-groups factor. A separate repeated-measures ANOVA was also used
to compare expected intoxication rating and performance decrements at
peak alcohol conditions. Within-day BAC levels for each gender were
compared using paired t tests (Sessions 2 vs. 6 and 3 vs. 5), and peak
BAC values were compared between men and women using independent t
tests. Regression analyses were used to examine the effects of expected
intoxication and BAC values on performance decrement. Finally, peak
performance decrement was related to self-reported alcohol use using
Pearson correlation.

Results

Overview and Placebo Effects

In addition to the 20 subjects who completed the study, 3 women and 2
men were also recruited but dismissed for presence of drugs in urine.
Rotary pursuit performance on the 2 placebo days was systematically
examined using a repeated-measures ANOVA, with session (1-6) and day
(Day 3 vs. 5) as the within-group factors and gender as the
between-group factor. This revealed no main effect of gender on rotary
pursuit performance, F(1, 18) = 1.628, p = .218, and a slight but
nonsignificant increase in performance following the first session of
the day, F(5, 90) = 2.058, p = .078. There was, however, a significant
effect of repeated testing (practice) in that mean contact time measured
during placebo day sessions increased from 106.8 s ([+ or -] SD 12.0) on
Day 3 to 108.9 s ([+ or -] 10.2) on Day 5 (main effect of day, F(1, 18)
= 7.124, p = .016. The Day x Gender interaction indicated that men and
women benefited from practice nearly equally, F(1, 18) = 0.00, p = .996.

BAC Values

As shown in Figure 1, BAC values on each of the two dose days reached
their peak prior to the fourth rotary pursuit session, after all three
beverage administrations. The multifactorial repeated-measures ANOVA
revealed a significant main effect of time (hourly alcohol doses) on BAC
levels, F(5, 90) = 101.59, p [less than] .001. The main effect of gender
revealed a trend toward higher BACs in female subjects, F(1, 18) = 4.02,
p = .06. There was no main effect of day of alcohol administration (Day
4 vs. Day 6) on BAC, F(1, 18) = 2.839, p = .109, nor was there a
significant Day x Gender interaction, F(1, 18) = 0.976, p = .336. The
peak BAC values between men and women were similar on both Day 4 (women:
0.11%, men: 0.10%; t(18) = 0.38, p = .71) and Day 6 (women: 0.12%, men:
0.11%; t(18) = 1.05, p = .31. Paired t tests indicated that on both
alcohol dose days, there were no differences in BAC between Session 2
and Session 6 or between Session 3 and Session 5 for either men or women
[ILLUSTRATION FOR FIGURE 1 OMITTED]. These similarities in BAC values
suggested that comparison of performance at Sessions 2 and 6 and
comparison of performance at Sessions 3 and 5 was appropriate for
examination of acute tolerance.

Rotary Pursuit Performance-General Intoxication Effects

A multifactorial repeated-measures ANOVA was performed comparing
rotary pursuit contact times obtained on the two alcohol administration
days. The time (session) of day and day of administration were
within-group factors and gender was a between-group factor. This
revealed significant main effects of session (time of day), F(5, 90) =
30.59, p [less than] .01, and gender, F(1, 18) = 5.15, p [less than] 04,
suggesting that in contrast to placebo, cumulative alcohol
administration significantly decreased time of contact in the rotary
pursuit task for both men and women, but that the rotary pursuit
performance of women was more adversely affected. In addition, there was
a main effect of day of alcohol administration on rotary pursuit
performance across all subjects, F(1, 18) = 5.07, p [less than] .04.
This indicated a slight tolerance to the effect of alcohol on rotary
performance from on the second day of alcohol administration (Day 6)
compared to the first (Day 4), and there was a trend for this tolerance
to be specific to men in that the Time x Gender x Day interaction was
nearly significant, F(5, 90) = 2.15, p [less than] .07.

Rotary Pursuit Performance-Peak Intoxication Effects

A separate repeated-measures ANOVA of Session 4 performance decrement
was performed in order to focus on peak intoxication effects. Here, the
day of alcohol administration was the single within-group factor and
gender was the between-group factor. This indicated no significant main
effects of day, F(1, 18) = 0.85, p = .37 or gender, F(1, 18) = 1.66, p =
.21. However, the Day x Gender interaction was significant, F(1, 18) =
9.60, p [less than] .01, and suggested that male subjects developed some
tolerance to the effects of peak alcohol intoxication on performance
from Day 4 to Day 6, whereas women developed some sensitivity to peak
alcohol effects.

Rotary Pursuit Performance-Acute Tolerance

To calculate the alcohol-induced performance decrements, the rotary
pursuit contact times during each of post-drink Sessions 2-6 were
subtracted from the contact time of that day's baseline session
(1). Mean alcohol-induced performance decrements are shown in Figure 2.
Paired t tests of performance decrements provided no evidence of acute
tolerance to alcohol in that performance decrements during Session 2
were not different from those of Session 6 for either men or women.
Similarly, there were no differences in performance decrement between
Sessions 3 and 5 for either gender. This was true for both dose days.

Subjects provided numerical ratings of both the "shot
equivalent" and the expected degree of intoxication on 0-10 scales.
The results indicate that subjects generally rated the placebo drinks as
containing at least one full "shot" worth of alcohol as well
as providing some degree of intoxication. These two ratings were
separately analyzed with repeated-measures analyses of variance, with
session (beverages 1-3) and dose (placebo vs. 0.35 g/kg alcohol) as
within-subject factors, and gender as a between-group factor. These
indicated that subjects rated the Day 4 alcohol doses as having greater
alcohol content, F(1, 18) = 6.676, p = .019, and causing greater
intoxication, F(1, 18) = 18.939, p [less than] .001, than placebo drinks
administrated on Day 3. Similarly, subjects rated the Day 6 doses as
having greater alcohol content, F(1, 18) = 6.135, p = .023), and causing
greater intoxication, F(1, 18) = 20.766, p [less than] .001, than
placebo drinks administrated on Day 5. There were no significant main
effects or interactions of gender.

To focus on the effect of repeated administration, peak expected
intoxication ratings (after the third 0.35 g/kg beverage) were compared
between Day 4 and Day 6 using an ANOVA, which indicated that main
effects of gender and day of administration were not significant.
However, the Gender x Day interaction was significant, F(1, 18) = 8.331,
p = .01, indicating that although men self-reported less expected
intoxication when consuming the second series of alcohol doses compared
to the first, women reported greater intoxication from the second series
of doses than they did the first.

Expectancy, BAC, and Performance Decrement

These gender-specific changes in alcohol expectancy across the two
alcohol administrations reflected the observed gender-specific
performance decrements. However, regression analyses indicated only
mild, nonsignificant relationships between self-reported expected
intoxication and performance decrement. Rather, these analyses revealed
a strong relationship between BAC levels and performance only on the
initial exposure day, but not the second. In each regression, Session 4
performance decrement (difference in contact time from prealcohol
baseline) was the dependent variable, and self-reported anticipated
intoxication following the third drink (expectancy) and Session 4 BAC
were the independent variables. On Day 4, expectancy and BAC together
accounted for most (55%) of the variance in performance decrement, F(2,
17) = 10.437, p = .001, with a high partial correlation between BAC and
performance decrement of .674, t(17) = 4.151, p [less than] .001, and a
trend toward a correlation between expectancy and decrement of .307,
t(17) = 1.89, p = .076. On Day 6, however, expectancy and BAC accounted
for only 21% of the variance in performance decrement, F(2, 17) = 2.292,
p = .131, neither of which had a significant partial correlation with
performance decrement (Expectancy r = .367, t(17) = 1.62, p = .122; BAC
r = .188, t(17) = .836, p = .415). The Day 4 and Day 6 regression
analyses were repeated for each gender separately and indicated no
gender differences, with a significant partial correlation found only
between BAC and decrement on Day 4 for both men, r = .691, t(7) = 2.92,
p = .022, and women, r = .729, t(7) = 2.50, p = .041.

Discussion

The cumulative dosing procedure used in this study provided an
opportunity to conduct performance testing at consistent times of the
day which corresponded to low, moderate, and high levels of alcohol
intoxication. Using this technique, we failed to find any evidence of
acute tolerance to the effect of alcohol on rotary pursuit performance
in either men or women. In both genders, mean rotary pursuit contact
time suffered after consumption of the first 0.35 g/kg beverage (which
resulted in mean BAC of .03 and above). The effect of BAC on performance
was consistent, whether the BAC was in the process of rising at the time
of testing (Sessions 2 and 3 in the morning), or whether it was falling
(Sessions 5 and 6 in the afternoon).

Of particular interest is that upon a second exposure to the three
alcohol doses, men seemed to develop some tolerance to the effects of
alcohol on performance at BAC values greater than 0.10, whereas women
developed some sensitivity. To our knowledge, this has not been
previously reported. Mild relationships between expectancy and
performance decrement were detected in that women expected greater
intoxication following the second series of three 0.35 g/kg alcohol
drinks compared to the first series and concomitantly performed worse on
the rotary pursuit task, whereas men predicted lower intoxication
following the second series of alcohol doses and performed better while
intoxicated the second time. Specific correlations between expectancy
self-rating and performance impairment may have reached significance
with a larger sample size. Moreover, performance decrements during the
second alcohol intoxication period were not specifically related to BAC
values, suggesting that gender-specific behavioral changes during the
second alcohol administration may have been largely due to some
behavioral factor as opposed to changes in alcohol pharmacokinetics.

In general, alcohol affected the performance of women to a greater
degree than men in that the main effect of gender on rotary pursuit
contact times was significant on alcohol administration days, whereas no
gender differences were observed on placebo days. Niaura et al. (1987)
reported no gender differences in rotary pursuit task performance under
alcohol conditions. Their study, however, featured only a single
administration of a much lower dose (0.65 g/kg) of alcohol, and it used
female subjects who drank slightly (but nonsignificantly) more than
males. Our findings parallel theirs in that peak performance decrement
after a single exposure to alcohol was similar for women and men, with
gender differences most apparent in this study during a repeated alcohol
exposure. Other studies which used a single alcohol exposure have
reported few consistent gender differences. For example, Taylor,
Dolhert, Friedman, and Mumenthaler (1996) studied male and female pilots
and found no significant gender differences in the effects of alcohol on
flight simulator performance. Hindmarch et al. (1991), using a
cognitive-behavioral battery of tests, found males more impaired than
females on some tasks, with no differences in other tasks. In contrast,
Avant (1990) found that females were more impaired by alcohol in a
visual detection task than males.

Cherpitel (1996) reported that whereas 3109 alcohol-related
emergency-room visits were more frequently violence-related among men, a
greater proportion of women compared to men suffered injuries related to
falls or motor vehicle accidents. Our findings suggest that a portion of
that gender difference may have been caused by differences in the
effects of alcohol on hand-eye coordination. A potential confound must
be considered, however. Although we roughly equalized peak intoxication
between men and women by reducing the dose for female subjects, there
was nevertheless a trend toward women having higher BAC levels than men
during non-peak sessions. This probably contributed to the overall main
effect of gender on rotary pursuit contact times recorded during the two
alcohol exposure days. In contrast, our main finding of gender
differences in performance decrement during a second exposure to BAC
[greater than] 0.10 may not have been due to pharmackinetics in that a
regression analysis indicated no relationship between specific BAC
readings and performance decrement. Nevertheless, similar BAC values
between men and women throughout all sessions would improve data
interpretation, and future studies should attempt to make further dosage
adjustments to minimize between-gender BAC differences along the
ascending and descending limbs of the BAC curve.

Interestingly, among these subjects (all of whom reported consuming
at least 5-6 drinks of alcohol per week), there was no correlation
between the effect of alcohol on performance and self-reported rates and
histories of alcohol consumption. The lack of significant correlations
here suggests that the greater effect of alcohol on the performance of
female subjects may not have been due to somewhat lower rates of weekly
alcohol consumption.

The mild parallels found here between expected intoxication and
performance decrement have been previously reported in studies of male
social drinkers. Fillmore and VogeI-Sprott (1995a) reported that
expected intoxication correlated positively with rotary pursuit
performance impairment, but that this relationship only holds for
experienced drinkers (Fillmore & VogeI-Sprott, 1995b). The
preliminary data from experienced social drinkers presented here
suggests that this relationship may hold for women as well.

In conclusion, the present study found no evidence for acute
tolerance on either day of exposure. However, a significant difference
was observed with respect to alcohol effects with male and female
subjects on the second day of exposure. These differences can be
attributed to what appears to be not just a small tolerance development
in males but perhaps a relatively large sensitivity effect in the female
subjects. An explanation for this result is beyond the scope of this
study and requires further research. This study, which presented two
alcohol exposures, does not provide the opportunity to assess whether
this sensitivity is a transitive phenomenon which would attenuate and
give way to the chronic tolerance development which has been reported
frequently in males (Bennett, 1992; Vogel-Sprott, 1992). Systematic
gender comparisons of alcohol-induced effects on performance and alcohol
pharmacokinetics across several days of exposure would be able to verify
these present findings as well as address the issue of gender
differences in tolerance development more fully.

We thank Sheila White and David Huang for their technical assistance.
This research was supported by the National Institute on Alcohol Abuse
and Alcoholism (AA-10095). Address all correspondence to Donald M.
Dougherty, Department of Psychiatry & Behavioral Sciences, 1300
Moursund Street, Houston, TX 77030. Phone: 713-500-2797, Fax:
713-500-2849, E-mail: ddoughrt.utmsimail@msi66.msi.uth.tmc.edu.